From modulational instability to focusing dam breaks in water waves

We report water wave experiments performed in a long tank where we consider the evolution of nonlinear deep-water surface gravity waves with the envelope in the form of a large-scale rectangular barrier. Our experiments reveal that, for a range of initial parameters, the nonlinear wave packet is not disintegrated by the Benjamin-Feir instability but exhibits a specific, strongly nonlinear modulation, which propagates from the edges of the wavepacket towards the center with finite speed. Using numerical tools of nonlinear spectral analysis of experimental data we identify the observed envelope wave structures with focusing dispersive dam break flows, a peculiar type of dispersive shock waves recently described in the framework of the semi-classical limit of the 1D focusing nonlinear Schr"odinger equation (1D-NLSE). Our experimental results are shown to be in a good quantitative agreement with the predictions of the semi-classical 1D-NLSE theory. This is the first observation of the persisting dispersive shock wave dynamics in a modulationally unstable water wave system

Apoptotic cell infusion treats ongoing collagen-induced arthritis, even in the presence of methotrexate, and is synergic with anti-TNF therapy

International audienceAbstractBackgroundApoptotic cell-based therapies have been proposed to treat chronic inflammatory diseases. The aim of this study was to investigate the effect of intravenous (i.v.) apoptotic cell infusion in ongoing collagen-induced arthritis (CIA) and the interaction of this therapy with other treatments used in rheumatoid arthritis (RA), including methotrexate (MTX) or anti-TNF therapy.MethodsThe effects of i.v. apoptotic cell infusion were evaluated in a CIA mouse model in DBA/1 mice immunized with bovine type II collagen. The number and functions of antigen-presenting cells (APC), regulatory CD4+ T cells (Treg), and circulating anti-collagen auto-antibodies were analyzed in CIA mice.ResultsTreatment of arthritic mice with i.v. apoptotic cell infusion significantly reduced the arthritis clinical score. This therapeutic approach modified T cell responses against the collagen auto-antigen with selective induction of collagen-specific Treg. In addition, we observed that APC from apoptotic-cell-treated animals were resistant to toll-like receptor ligand activation and favored ex vivo Treg induction, indicating APC reprogramming. Apoptotic cell injection-induced arthritis modulation was dependent on transforming growth factor (TGF)-β, as neutralizing anti-TGF-β antibody prevented the effects of apoptotic cells. Methotrexate did not interfere, while anti-TNF therapy was synergic with apoptotic-cell-based therapy.ConclusionOverall, our data demonstrate that apoptotic-cell-based therapy is efficient in treating ongoing CIA, compatible with current RA treatments, and needs to be evaluated in humans in the treatment of RA

Harnessing Apoptotic Cell Clearance to Treat Autoimmune Arthritis

Early-stage apoptotic cells possess immunomodulatory properties. Proper apoptotic cell clearance during homeostasis has been shown to limit subsequent immune responses. Based on these observations, early-stage apoptotic cell infusion has been used to prevent unwanted inflammatory responses in different experimental models of autoimmune diseases or transplantation. Moreover, this approach has been shown to be feasible without any toxicity in patients undergoing allogeneic hematopoietic cell transplantation to prevent graft-versus-host disease. However, whether early-stage apoptotic cell infusion can be used to treat ongoing inflammatory disorders has not been reported extensively. Recently, we have provided evidence that early-stage apoptotic cell infusion is able to control, at least transiently, ongoing collagen-induced arthritis. This beneficial therapeutic effect is associated with the modulation of antigen-presenting cell functions mainly of macrophages and plasmacytoid dendritic cells, as well as the induction of collagen-specific regulatory CD4+ T cells (Treg). Furthermore, the efficacy of this approach is not altered by the association with two standard treatments of rheumatoid arthritis (RA), methotrexate and tumor necrosis factor (TNF) inhibition. Here, in the light of these observations and recent data of the literature, we discuss the mechanisms of early-stage apoptotic cell infusion and how this therapeutic approach can be transposed to patients with RA

Role of the basin boundary conditions in gravity wave turbulence

Gravity wave turbulence is studied experimentally in a large wave basin where irregular waves are generated unidirectionally. The role of the basin boundary conditions (absorbing or reflecting) and of the forcing properties are investigated. To that purpose, an absorbing sloping beach opposite to the wavemaker can be replaced by a reflecting vertical wall. We observe that the wave field properties depend strongly on these boundary conditions. Quasi-one dimensional field of nonlinear waves propagate before to be damped by the beach whereas a more multidirectional wave field is observed with the wall. In both cases, the wave spectrum scales as a frequency-power law with an exponent that increases continuously with the forcing amplitude up to a value close to -4, which is the value predicted by the weak turbulence theory. The physical mechanisms involved are probably different according to the boundary condition used, but cannot be easily discriminated with only temporal measurements. We have also studied freely decaying gravity wave turbulence in the closed basin. No self-similar decay of the spectrum is observed, whereas its Fourier modes decay first as a time power law due to nonlinear mechanisms, and then exponentially due to linear viscous damping. We estimate the linear, nonlinear and dissipative time scales to test the time scale separation that highlights the important role of a large scale Fourier mode. By estimation of the mean energy flux from the initial decay of wave energy, the Kolmogorov-Zakharov constant is evaluated and found to be compatible with a recent theoretical value.Comment: Journal of Fluid Mechanics, Cambridge University Press (CUP), 2015, in press in JF

Direct Imaging and Spectroscopy of Extrasolar Planets

Direct imaging and spectroscopy is the likely means by which we will someday identify, confirm, and characterize an Earth-like planet around a nearby Sun-like star. This Chapter summarizes the current state of knowledge regarding discovering and characterizing exoplanets by direct imaging and spectroscopy. We detail instruments and software needed for direct imaging detections and summarize the current inventory of confirmed and candidate directly-imaged exoplanets. Direct imaging and spectroscopy in the past decade has provided key insights into jovian planet atmospheres, probed the demographics of the outskirts of planetary systems, and shed light on gas giant planet formation. We forecast the new tools and future facilities on the ground and in space that will enhance our capabilities for exoplanet imaging and will likely image habitable zone rocky planets around the nearest stars.Comment: 34 pages; 19 figures; Review of the Direct Imaging field in Protostars and Planets VII; in pres

166 Balloon aortic valvuloplasty in unstable and critically ill patients: analysis of three strategies

AimThanks to improved technology and the advent of transcatheter aortic valve implantation (TAVI), balloon aortic valvuloplasty (BAV) has reappared in the management of high risk patients with severe aortic stenosis in a critical clinical state in three different therapeutic strategies: 1) palliative care [A] 2) bridge to surgery [B] 3) bridge to TAVI [C]. Our main objective was to assess the safety, the effiency and the pertinence of BAV.MethodsThirty six patients with severe aortic stenosis and prohibitive surgical risk (logistic Euroscore>15% or severe commorbidities) underwent 39 BAV: 8 in strategy A, 20 in strategy B, 11 in strategy C. 3 patients underwent a second BAV due to early restenosis.ResultsThere was a significant improvement of the hemodynamic parameters after BAV: the peak to peak transaortic gradient was reduced by 56% (47mmHg vs 30mmHg; p<0.001) and index valve area was increased by 48% (0.35 vs 0.52cm2/m2; p<0.001). There was no severe procedural complication (no death due to procedure, no massive aortic insuffisiency, no tamponade). Two patients (5.1%) needed a pacemaker implantation for postprocedure atrioventricular block and 6 patients (15.4%) had moderate bleeding of the femoral artery site. The mortality and follow up for the three strategies are summarized in the table.ConclusionBAV is a safe and efficient transient therapeutic strategy for patients with severe aortic stenosis with prohibitive surgical risk. BAV appears to be more pertinent in bridge to surgery or brige to TAVI than in palliative care. For patients in critical clinical state, BAV stabilizes the hemodynamic status and allows the assessment of anatomical selection criteria for TAVIStratégy A(n=8)Stratégy B(n=20)Stratégy C(n=11)Age (mean, min-max)80 (61–94)73 (44–85)81 (60–87)Mean logistic Euroscore (%)4822.644.2Death n (%)6 (75)8 (40)5 (45)Cardiovascular death n (%)4 (50)3 (15)2 (18)Time of occurrence (days, min-max)12 (0–47)66 (0–130)155 (10–316)Aortic valve replacement n (%)-14 (70)-TAVI n (%)--2 (18

Gated blood-pool SPECT evaluation of changes after radiofrequency catheter ablation of accessory pathways Evidence for persistent ventricular preexcitation despite successful therapy

AbstractOBJECTIVESThis study was designed to prospectively evaluate the effects of radiofrequency ablation in Wolff-Parkinson-White (WPW) syndrome by scintigraphic analysis.BACKGROUNDThe functional changes triggered by radiofrequency current ablation of atrioventricular accessory pathways are not fully known.METHODSForty-four patients with WPW syndrome were consecutively investigated before and 48 h after radiofrequency therapy. Fourteen patients had right sided atrioventricular pathways and 30 patients had left sided bypass-tracts. Planar gated imaging and gated blood pool tomography were performed in all of these patients.RESULTSA significant increase in the left ventricular ejection fraction (LVEF) was demonstrated in patients with left preexcitation (62.2 ± 7.9% before ablation against 64.4 ± 6.3% after ablation, p = 0.02) but not for those with right sided anomalous pathway. Phase analysis only gave significant differences following ablation of right sided pathways (left-to-right phase difference = 14.4 ± 13.8° before ablation versus 7.5 ± 7.2° after ablation, p < 0.05). Early abnormal ventricular contraction persisted in 12 patients with right accessory pathways and in 8 patients with left accessory pathways despite the complete disappearance of any abnormal conduction as proven electrophysiologically.CONCLUSIONSFollowing catheter ablation of atrioventricular accessory pathways: 1) an improvement of left ventricular function may be seen, particularly in patients with left sided accessory pathways, and 2) unexpected persistence of local ventricular preexcitation at the site of successful ablation may be detected

Effect of Cyclosporine on Left Ventricular Remodeling After Reperfused Myocardial Infarction

ObjectivesThis study examined the effect of a single dose of cyclosporine administered at the time of reperfusion on left ventricular (LV) remodeling and function by cardiac magnetic resonance 5 days and 6 months after myocardial infarction.BackgroundIn a human study, administration of cyclosporine at the time of acute reperfusion was associated with a smaller infarct size.MethodsTwenty-eight patients of the original cyclosporine study had an acute (at 5 days) and a follow-up (at 6 months) cardiac magnetic resonance study to determine LV volumes, mass, ejection fraction, myocardial wall thickness in infarcted and remote noninfarcted myocardium, and infarct size.ResultsThere was a persistent reduction in infarct size at 6 months in the cyclosporine group compared with the control group of patients (29 ± 15 g vs. 38 ± 14 g; p = 0.04). There was a significant reduction of LV end-systolic volume (and a trend for LV end-diastolic volume; p = 0.07) in the cyclosporine group compared with the control group, both at 5 days and 6 months after infarction. There was no significant difference between the 2 groups in either global LV mass or regional wall thickness of the remote noninfarcted myocardium at 5 days or 6 months. Attenuation of LV dilation and improvement of LV ejection fraction by cyclosporine at 6 months were correlated with infarct size reduction.ConclusionsCyclosporine used at the moment of acute myocardial infarction reperfusion persistently reduces infarct size and does not have a detrimental effect on LV remodeling. These results are preliminary and must be supported by further studies. (Ciclosporin A and Acute Myocardial Infarction; NCT00403728

BEAST detection of a brown dwarf and a low-mass stellar companion around the young bright B star HIP 81208

Recent observations from B-star Exoplanet Abundance Study (BEAST) have illustrated the existence of sub-stellar companions around very massive stars. In this paper, we present the detection of two lower mass companions to a relatively nearby ($148.7^{+1.5}_{-1.3}$ pc), young ($17^{+3}_{-4}$ Myr), bright (V=$6.632\pm0.006$ mag), $2.58\pm0.06~ M_{\odot}$ B9V star HIP 81208 residing in the Sco-Cen association, using the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument at the Very Large Telescope (VLT) in Chile. Analysis of the photometry obtained gives mass estimates of $67^{+6}_{-7}~M_J$ for the inner companion and $0.135^{+0.010}_{-0.013}~M_{\odot}$ for the outer companion, indicating the former to be most likely a brown dwarf and the latter to be a low-mass star. The system is compact but unusual, as the orbital planes of the two companions are likely close to orthogonal. The preliminary orbital solutions we derived for the system indicate that the star and the two companions are likely in a Kozai resonance, rendering the system dynamically very interesting for future studies.Comment: 18 pages, 14 figures, 5 tables Accepted for publication in the 10. Planets and planetary systems section of A&